Crystal oscillators generate timing signals for many components of communication devices (e.g., smartphones). For example, crystal oscillators may be used to generate a highly accurate reference clock signal that, in turn, may be used by frequency synthesizers to generate RF carrier signals (e.g., to facilitate wireless data transmissions). Crystal oscillators may also be used to generate low-power real-time clock (RTC) signals that, in turn, may be used for timekeeping functions during low-power modes (e.g., to allow a mobile station to wake-up from a sleep state at certain intervals to listen for beacon transmissions from an associated access point). As a result, communication devices typically include one crystal oscillator to generate the high frequency reference clock signals and include another crystal oscillator to generate the low-power RTC signals. However, the inclusion of multiple crystal oscillators in a communication device may consume a significant amount of circuit area and increase cost.
Thus, there is a need to provide an oscillator circuit that may selectively generate relatively high-accuracy clock signals and relatively low-power clock signals using a single crystal.